This principle applies to the attempted eradication of all defects or imperfect uses of the mental and physical mechanisms in all the acts of daily life and in such games as cricket, football, billiards, baseball, golf, etc., and in the physical manipulation of the piano, violin, harp and all such instruments. My reader must not fail to remember that mental conceptions are the stimuli to the ideo-motor centre which passes on the subconscious or conscious guiding orders to the mechanism. In dealing with human defects or imperfections we must consider the inherited subconscious conceptions associated with the mechanisms involved, and also the conceptions which are to be the forerunners of the ideo-motor guiding orders connected with the new and correct use of the different mechanisms. In order to establish successfully the latter (correct conception), we must first inhibit the former (incorrect conception), and from the ideo-motor centre project the new and different directing orders which are to influence the complexes involved, gradually eradicating the tendency to employ the incorrect ones, and steadily building up those which are correct and reliable. It will therefore be understood that if we eliminate the conception established and associated with our defects or imperfections, it means that we are really eliminating our inherited subconsciousness, and all the defective uses of the psycho-physical mechanism connected therewith. In our attempts on these lines we are, at the outset, confronted with the difficulty of mental rigidity. The preconceptions and habits of thought with regard to the uses of the muscular mechanisms are the first if not the only stumbling-blocks to the teaching of conscious control. Many of these preconceptions are the legacy of instinct, others arise from habitual practices started by a faulty comprehension of the uses of the mechanism, others again by conscious or unconscious imitation of faults in others. In this last case it may be noted that although we are always deploring the degeneracy of civilised man the exemplars held up for the child’s conscious and unconscious imitation are nearly always faulty specimens. These preconceptions and habits of thought, therefore, must be broken down, and since the reactions of mind on body and body on mind are so intimate, it is often necessary to break down these preconceptions of mind by performing muscular acts for the subject vicariously; that is to say, the instructor must move the parts in question while the subject attends to the inhibition of all muscular movements. It would be impossible, however, to describe the method in full detail in this place, owing to the extraordinary variability of the cases presented, no two of which exhibit precisely the same defects. On broad lines it is evident that the misuses must be diagnosed by the instructor who may be called upon to use considerable ingenuity and